JPH0764104B2 - Paper feed control circuit for serial printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed control circuit of a serial printer having a 4-phase pulse motor for paper feed.

(Prior Art) FIG. 2 shows a main configuration of a paper feeding mechanism of a serial printer. Rotation of a paper feeding four-phase pulse motor 2 mounted on the side frame 1 is the same as that of the side frame 1.
Is transmitted to the platen 3 rotatably supported by the bearing portion 1a of the sheet through the reduction gears 4 and 5, and is also transmitted to a pin tractor (not shown). It is supposed to be sent.

FIG. 3 is a front view of a print head used in a serial printer having the above-described paper feed mechanism and shows an example of print characters thereof. The print head 6 has nine pins 7 having circular end faces. However, for example, they are arranged in a line vertically with a pitch of 1/72 inch. The print head 6 is sent by a carriage (not shown) in a direction orthogonal to the paper feed direction, and in the process, only predetermined pins are sequentially hit on the print paper via an ink ribbon (not shown) to print characters. 8 is printed.

By the way, when feeding paper in such a serial printer, a predetermined amount of print paper, for example 1/6, is used for line feed.
There are an ordinary paper feed mode including an inch feed line feed mode and a mode equivalent thereto, and a minute paper feed mode in which a small amount, for example, 1/144 inch is fed to hit a character with high print quality or an emphasized character.

FIG. 4 (a) shows an example of a print character according to the line feed mode. The character 10 is printed at a position shifted by 1/6 inch with respect to one print character 9, that is, a line feed position.
Further, FIG. 4 (b) shows an example of a print character in the minute paper feed mode, which is displaced by 1/144 inch with respect to the first print character 11 composed of diagonally shaded dots,
That is, it is composed of white dots at the position where the small paper is fed.
The print character 12 for the second time is applied, and the character 11 and 12 constitute a high-quality character 13 with few gaps between dots.
A method of printing one character in two times is called a two-pass printing method, and a character printed by this method is called a two-pass printing character.

FIG. 5 shows a drive system of a conventional four-phase pulse motor 2. In the figure, 2-1, 2-2, 2-3 and 2-4 are motor 1's.
Phase, 2-phase, 3-phase and 4-phase excitation phases, 14 is a paper feed control circuit,
Reference numeral 15 is a driver circuit. The paper feed control circuit 14 receives a paper feed request signal sent from a main controller (not shown) of the serial printer, and generates preset phase excitation signals φ1, φ2, φ3 and φ4.

FIG. 6 shows an example of the phase excitation signals .phi.1 to .phi.4, and here shows an example of signals by the well-known two-phase excitation method. That is, in this method, the phase excitation signals for two consecutive phases, for example, (φ1, φ2) are turned on at the same time, and thereafter (φ2, φ3) at every predetermined excitation phase switching timing,
The phases to be turned on are sequentially switched such that (φ3, φ4), (φ4, φ1), (φ1, φ2), ....

The driver circuit 15 supplies the actual drive current to the phases 2-1 to 2-4 of the motor 2 in which the phase excitation signals φ1 to φ4 are ON, and drives the motor 2.

(Problems to be Solved by the Invention) By the way, in the above serial printer, assuming that 1/288 inch paper is fed by one switching of the excitation phase in the motor 2, 1/6 inch paper feeding, that is, line feed. In order to do this, it is necessary to switch the excitation phase 48 times.
In order to feed the inch paper, that is, to feed the minute paper, it is necessary to switch the excitation phase twice.

When the excitation phase before paper feeding (hereinafter referred to as the stop phase) is, for example, the (1,2) phase, and when the above-described minute paper feeding is executed, the excitation phase is (2,3) phase, (3, 4) The phases are sequentially switched, but the energy generated in the motor 2 at this time is almost the same as the energy associated with the switching of the excitation phase twice in the normal paper feed mode, and is slightly excessive for minute paper feed. It becomes energy.

As a result, in the minute paper feed mode, the portion of the platen 3 closer to the motor is lifted in the direction of arrow A in FIG. However, there is a problem that extra paper is fed by that amount, and as a result, dot misalignment occurs in the two-pass print character, resulting in poor print quality.

FIG. 7 shows the dot deviation described above. In the figure, 16 is the dot of the first printed character, 17 is the dot of the second printed character that is offset from the dot 16 by K (> 1/144 inch). The dot, 18 originally represents the dot of the second printed character to be printed.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and to provide a paper feed control circuit for a serial printer capable of feeding a print paper accurately by a small amount and printing high-quality two-pass print characters.

(Means for Solving Problems) In order to solve the above problems, the present invention includes a four-phase pulse motor as a paper feeding motor, and switches between a normal paper feeding mode including a line feed mode and two excitation phases. In a paper feed control circuit of a serial printer that generates a phase excitation signal for the paper feed motor of a serial printer having a micro paper feed mode based on A determination means for determining whether the paper feed mode is set, and a first phase excitation signal generated by a normal two-phase excitation method corresponding to the normal paper feed mode.
When the stop phase is the (N, N + 1) phase corresponding to the phase excitation signal generating means and the fine paper feed mode, the (N + 2) phase, (N
The second phase excitation signal generating means for sequentially generating the phase excitation signals corresponding to the +2, N + 3) phases is provided.

(Operation) According to the present invention, when the paper feeding request inputted from the main controller of the serial printer is judged by the judging means to be the normal paper feeding, the first phase excitation signal generating means causes the normal two-phase A phase excitation signal according to the excitation method is generated, whereby two of the excitation phases of the motor are always excited and driven at the same time, and when it is determined that the minute paper feed has occurred, the second phase excitation signal generating means is generated. Than (N + 2) phase, (N
+ 2, N + 3) phase excitation signals are sequentially generated, which first excites the next one of the stop phases of the motor's excitation phases, and further simultaneously with the next one of the stop phases. It is excited and driven.

(Embodiment) FIG. 1 shows the configuration of a drive system of a four-phase pulse motor having a paper feed control circuit according to the present invention. In the figure, the same components as those of the conventional example are designated by the same reference numerals. That is, 2 is a 4-phase pulse motor, 2-1 to 2-4 are excitation phases of 1 to 4 phases of the motor 2, 15 is a driver circuit, and 20 is a paper feed control circuit.

The paper feed control circuit 20 includes a paper feed request signal determination means 21, a first phase excitation signal generation means 22 and a second phase excitation signal generation means 23.

The paper feed request signal determination means 21 receives a paper feed request signal input from the outside, for example, a main controller of a serial printer, and if this is for a normal paper feed mode, the first phase excitation signal generation means 22. And for the fine paper feed mode, the second phase excitation signal generating means 23 is started.

Further, the first phase excitation signal generating means 22 generates phase excitation signals φ1 to φ4 according to a well-known two-phase excitation method corresponding to the normal paper feed mode including the line feed mode.

Further, the second phase excitation signal generating means 23, when the stop phase is the (N, N + 1) phase corresponding to the fine paper feed mode, (N +
2) Phase excitation signals corresponding to the phase and the (N + 2, N + 3) phase are sequentially generated.

FIG. 8 shows an example of the phase excitation signals .phi.1 to .phi.4 generated by the second phase excitation signal generating means 23. When the phase excitation signals .phi.1 and .phi.2 are turned on before the paper is fed, the first time. At the excitation phase switching timing, only the phase excitation signal φ3 turns on and 2
The phase excitation signals φ3 and φ4 are turned on at the timing of switching the excitation phase for the first time.

Therefore, when the minute paper feed is performed from the state in which the excitation phases 2-1 and 2-2 of the motor 2 are excited and stopped, first,
Only excitation phase 2-3 is excited, then excitation phases 2-3 and 2
-4 is excited and driven.

FIG. 9 is a graph showing the relationship between the torque (T) generated in the motor 2 and the phase (θ) in the fine paper feed mode.
The curve 31 shown by the solid line is based on the phase excitation signal generated by the paper feed control circuit 20 of the present invention, and the curve 32 shown by the alternate long and short dash line is based on the phase excitation signal generated by the conventional paper feed control circuit 14. is there. In the graph, the product of torque and phase (T · θ), that is, the area of the portion surrounded by each curve and the horizontal axis shows the energy generated in the motor 2, and the phase excitation signal according to the present invention is more It can be seen that the area is small and the generated energy is small.

FIG. 10 is a graph showing the change in the speed of the motor 2 in the minute paper feed mode. In the figure, the curve 33 shown by the solid line is due to the phase excitation signal generated by the paper feed control circuit 20 of the present invention. , The curve 34 indicated by the broken line is a conventional paper feed control circuit
This is due to the phase excitation signal generated from 14. In the graph, comparing the rising edges of the curve 33 and the curve 34, it can be seen that the curve 33 is slower.

As described above, according to the present invention, the energy generated by the motor 2 in the minute paper feed mode can be reduced,
In addition, since the change in the rising speed of the motor 2 can be moderated, the portion of the platen 3 near the motor is not lifted and the print paper is not fed by that amount, unlike the conventional case. As a result, the print quality of the 2-pass print character is not impaired. Needless to say, the operation in the normal paper feed mode is the same as the conventional one.

FIG. 11 is a flow chart showing a program when the paper feed control circuit 20 is realized by a microprocessor, and FIG. 12 shows the contents of the table corresponding to the flow chart.

In FIG. 11, A is a variable indicating the stop phase, and the numerical values “1”, “2”, “3” and “4” are the stop phase (1,2).
It corresponds to the phase, (2,3) phase, (3,4) phase and (4,1) phase, respectively. Further, the next excitation phase information indicates the excitation phase and non-excitation phase of each excitation phase when the paper is fed from the stopped state, and the fine paper feed mask data is usually used in the fine paper feed mode. 2 shows the phases that are not excited as compared with the two-layer excitation method, and these are represented by 4-bit information corresponding to 1, 2, 3 and 4 phases, respectively, as shown in FIG. The phase is indicated by bit "1", and the non-excited phase is indicated by bit "0".

(Effect of the Invention) As described above, according to the present invention, it is possible to reduce the energy generated by the motor in the minute paper feed mode, and to moderate the change in the motor rising speed. Therefore, it is possible to feed a small amount of paper to the paper, and therefore it is possible to print out a 2-pass print character with good print quality.

[Brief description of drawings]

FIG. 1 is a diagram showing a drive system of a four-phase pulse motor provided with a paper feed control circuit of a serial printer of the present invention, FIG. 2 is a diagram showing a main configuration of a paper feed mechanism of a serial printer, and FIG.
FIG. 4 is a view showing the print head as viewed from the front and an example of the print characters thereof, FIGS. 4 (a) and 4 (b) are views showing an example of the print characters in the line feed mode and the minute paper feed mode, and FIG. The figure which shows the drive system of the conventional 4-phase pulse motor, FIG. 6 is the figure which shows the phase excitation signal by a 2-phase excitation system,
FIG. 7 is a diagram showing dot misalignment due to feeding of fine paper, and FIG.
FIG. 9 is a diagram showing a phase excitation signal in the micro paper feeding mode according to the present invention, FIG. 9 is a graph showing a relationship between torque and phase generated in the motor in the micro paper feeding mode, and FIG. 10 is a micro paper feeding mode. FIG. 11 is a graph showing a change in motor speed at the time, FIG. 11 is a flow chart showing an embodiment of the paper feed control circuit of the present invention, and FIG. 12 is a view showing contents of a table corresponding to the flow chart of FIG. . 2 ... 4-phase pulse motor, 20 ... Paper feed control circuit, 21 ...
... paper feed request signal determination means, 22 ... first phase excitation signal generation means, 23 ... second phase excitation signal generation means.

Claims (1)

[Claims] 1. A paper feed motor for a serial printer, comprising a four-phase pulse motor as a paper feed motor, and having a normal paper feed mode including a line feed mode and a minute paper feed mode based on two switching of excitation phases. In the paper feed control circuit of the serial printer that generates the phase excitation signal for the paper feed control circuit, a judgment means for judging whether the paper feed request inputted from the outside is the normal paper feed mode or the fine paper feed mode, When the first phase excitation signal generating means for generating a phase excitation signal by a normal two-phase excitation method corresponding to the feeding mode and the stop phase corresponding to the micro paper feeding mode are (N, N + 1) phases, A paper feed control circuit for a serial printer, comprising: a second phase excitation signal generating means for sequentially generating phase excitation signals corresponding to the (N + 2) phase and the (N + 2, N + 3) phase.